BevShores2019

An Integrated Physical-Social-Community (PSC) Approach for Sustainable Shore Protection, Beach Integrity, and Bluff/Dune Stabilization Along Lake Michigan

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Beverly Shores 2019 1500 x 600

Beverly Shores, IN beach

Recent record-high water levels across the Laurentian Great Lakes have shoreline communities scrambling to protect beaches, property, and infrastructure from rapid and widespread erosion. This current situation, and the uncertainty associated with lake levels in the future, underscores the need for comprehensive shoreline management strategies that will create resilient shorelines capable of buffering future conditions. However, shoreline protection strategies must be carefully implemented, ideally in a coordinated manner, since “hard” protection measures such as sea walls and revetments generally have large impacts on neighboring shorelines. Additionally, shoreline management does not merely involve applications of engineering principles to solve the problem; shorelines are highly social systems that require careful consideration of social and community perspectives.

This collaborative project, jointly funded by the Illinois-Indiana, Michigan, and Wisconsin Sea Grants tackles key physical, social, and community challenges associated with Lake Michigan shorelines. At Purdue we are particularly focused on the Illinois and Indiana shorelines, seeking to not only understand the physical mechanisms associated with the current shoreline state and erosion, but also to place the current state in historical perspective. Our work involves shoreline surveys (terrestrial and bathymetric), nearshore hydrodynamic and sediment measurements, and analysis of historical aerial imagery. Additional work by Dr. Aaron Thompson at Purdue is examining the attitudes and perceptions of Indiana and Illinois shoreline communities, particularly with respect to shoreline protection alternatives.

Funding

Illinois-Indiana Sea Grant, Michigan Sea Grant, Wisconsin Sea Grant

Collaborators

Chin Wu, University of Wisconsin-Madison; Guy Meadows and Pengfei Xue, Michigan Tech; Mark Brederland, Michigan State University; Aaron Thompson, Purdue University; and others.

Habib UAV

Evaluation of UAV LiDAR for mapping coastal Environments

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Unmanned Aerial Vehicle (UAV)-based remote sensing techniques have demonstrated great potential for monitoring rapid shoreline changes. With image-based approaches utilizing Structure from Motion (SfM), high-resolution Digital Surface Models (DSM), and orthophotos can be generated efficiently using UAV imagery. However, image-based mapping yields relatively poor results in low textured areas as compared to those from LiDAR. This study demonstrates the applicability of UAV LiDAR for mapping coastal environments. A custom-built UAV-based mobile mapping system is used to simultaneously collect LiDAR and imagery data. The quality of LiDAR, as well as image-based point clouds, are investigated and compared over different geomorphic environments in terms of their point density, relative and absolute accuracy, and area coverage. The results suggest that both UAV LiDAR and image-based techniques provide high-resolution and high-quality topographic data, and the point clouds generated by both techniques are compatible within a 5 to 10 cm range. UAV LiDAR has a clear advantage in terms of large and uniform ground coverage over different geomorphic environments, higher point density, and ability to penetrate through vegetation to capture points below the canopy. Furthermore, UAV LiDAR-based data acquisitions are assessed for their applicability in monitoring shoreline changes over two actively eroding sandy beaches along southern Lake Michigan, Dune Acres, and Beverly Shores, through repeated field surveys. The results indicate a considerable volume loss and ridge point retreat over an extended period of one year (May 2018 to May 2019) as well as a short storm-induced period of one month (November 2018 to December 2018). The foredune ridge recession ranges from 0 m to 9 m. The average volume loss at Dune Acres is 18.2 cubic meters per meter and 12.2 cubic meters per meter within the one-year period and storm-induced period, respectively, highlighting the importance of episodic events in coastline changes. The average volume loss at Beverly Shores is 2.8 cubic meters per meter and 2.6 cubic meters per meter within the survey period and storm-induced period, respectively.